The program, Modeling Immunity for Biodefense, will develop novel or improved highly predictive mathematical models that simulate immune function. These model systems will be developed for analysis of host immune responses to NIAID category A-C pathogens, and may apply to other infectious and immune-mediated diseases. Knowledge gained from these studies will: advance our understanding of the delicate balance required to induce protective immunity;guide laboratory experiments of host immune responses;and lay the foundation for development of models that can extrapolate human immune responses to infection or immune-mediated diseases based on results from relevant in vitro and in vivo studies.